Holocene carbonate facies model, Ras Shukhier hypersaline pool and its surrounding sabkha, west Gulf of Suez, Egypt

Abstract

The Holocene Ras Shukhier pool is an active carbonate depositional subenvironment surrounded by an evaporitic supratidal sabkha. Field and petrographic studies of the carbonate constituents of the pool lead to the recognition of seven sedimentary facies. These are: (1) carbonate lithoclast-pellet-aggregate sand facies, (2) algal (cyanophyt) stromatolites comprising stratiform cryptalgal laminites and laterally close-linked hemispheroids (LLH-C), (3) pellet-lime mud with dolomitized bioclastic floatstone/packstone crusts, (4) pellet-lime mud facies, (5) gastropod ( Cerithium) pellet-lime muddy sand facies, (6) puffy gypsum crust, and (7) tufa limestone patches. The lateral distribution of the carbonate facies in the pool is dependent on the orientation of the pool with respect to the prevailing northwest winds and on the direction of water seepage. The evaporitic sabkha is classified here into: (a) a seasonally water-covered rim where the carbonates and evaporites formed seasonally by direct precipitation from the surface water, and (b) a subaerially exposed sabkha with lithified halite crust exhibiting tepee structures. The occurrence of carbonates, followed by sulphates and halites, within the sabkha siliciclasts, have been developed by sedimentation from brines migrating upward.